Single-phase AC motor

A single-phase AC motor is a rotating electromagnetic machine used to realize the mutual conversion of electrical energy and mechanical energy.

The starting methods of 220V AC single-phase motors are roughly divided into the following categories:

The first type, the split-phase starting type, as shown in Figure 1, is assisted by the auxiliary starting winding, and its starting torque is not large. The operating speed remains roughly constant. Mainly used in electric fans, air conditioner fan motors, washing machines and other motors.

The second is that the starting winding does not participate in the running work, and the motor continues to operate with the running winding coil, as shown in Figure 2.

The third type is that the centrifugal switch is turned on when the motor is stationary. After the power is supplied, the starting capacitor participates in the starting work. When the rotor speed reaches 70% to 80% of the rated value, the centrifugal switch will automatically trip, and the starting capacitor completes the task. is disconnected. The running capacitor is connected in series with the starting winding to participate in the running work. This connection method is generally used in places where the load is large and unstable, such as air compressors, cutting machines, and woodworking machines. Figure 3.

For motors with centrifugal switches, if the motor cannot be successfully started in a short time, the winding coils will burn out quickly.

Capacitance value: dual-value capacitor motor, large starting capacitance, small running capacitance, withstanding voltage generally greater than 400V

Forward and reverse control:

Figure 1, Figure 2, Figure 3, forward and reverse control, only need to swap 1-2 lines or 3-4 lines to complete the reversal.

For the judgment of the starting and running windings in Figure 1, Figure 2, and Figure 3, the DC resistance of the starting winding is usually much larger than that of the running winding, which can be measured with a multimeter. Generally, the DC resistance of the running winding is several ohms, while the DC resistance of the starting winding is ten ohms to several tens of ohms.